a word skeptics use as shorthand to describe pseudo-scientific and often anti-scientific ideas – ideas that are irrational and not based on evidence commensurate with the extraordinary nature of the claim.

SkepticWiki’s definition includes those who hold unsubstantiated beliefs, as does Skeptico.

We do not.

In recent years, the term has been used to describe just about everything in the skeptical community’s cross hairs and our definition is fairly broad. In general, woo includes ideas and practices, regardless of popularity or age, which are based on a claim which meets one or more of the following criteria:

requires unreasonable assumptions

is not testable (so it requires unreasonable assumptions)

is not supported by evidence despite testing

refutes current knowledge without sufficient evidence

We call such claims “extraordinary” and, as such, they require extraordinary evidence if we are to accept them as true.